Sinner
by dog-tooth
Summary: Upon Mycroft's arrival at Baker Street, Sherlock's told a secret that's been kept from him for twenty two years. With murders occurring across over London, can Sherlock solve the case and look after those close to him before it's too late? M later on.
1. Chapter 1

**Sinner**

**Chapter 1**

John Watson had to admit that it was nice to finally have a day off. All day the wind had screamed and the rain had beaten against the windows, meaning that even Sherlock had been forced to accept that it would be wise to stay in.

Sherlock was currently sprawled out on the chair, his long legs stretched languidly in front of him. For most of the day he had seemed content reading some scientific book that John had little knowledge of. However he was currently stood by the window, staring out at the elemental forces with a scowl on his face.

John didn't look up from his own book as Sherlock spoke, scorn evident in his voice. "It's ridiculous, John."

He sighed. "It's October, Sherlock. It's what the weather does."

"Yes but why now." He bounced irritably on the balls of his feet and threw his hands up into the air. "I'm bored."

John couldn't help but compare him to a child. He half expected him to start throwing some kind of tantrum. "Why don't you go and work on one of your experiments? That one on the kitchen table still hasn't done anything."

He turned quickly to face him, before starting to pace around the room. "I can't. The ears exploded in the microwave and _somebody_ removed the fingers from the bathtub." He glared at John before continuing his pacing.

"How am I expected to shower with fingers in the bath?"

Sherlock didn't answer but came to a sudden halt and sighed. "Mycroft's here. Something's wrong."

John looked up from his book, startled. "Mycroft? How an earth did you know that?"

Once again he ignored John and threw himself back into his chair, his legs once again stretched dangerously across the floor.

Footsteps sounded up the stairs, confirming Sherlock's theory. John placed the book back on the table just as the door opened. Surprisingly Mrs Hudson was not with him, and he assumed that she must have been out. He found it odd, especially in this kind of weather. However, he wasn't surprised however to see that Mycroft had not bothered to knock.

"You finally got some proper use out of that umbrella then," Sherlock observed, a mocking smile on his face as he watched his brother place the slightly damp object against the wall.

Mycroft didn't answer but the corner of his mouth pulled down slightly.

Sherlock was the first to notice the paleness of his brother's skin and his heavy eyes, features shown only on a man weighed down with some great anxiety. On further observation he noticed that his tie wasn't tied as neatly as it usually was and his shirt had become slightly un-tucked from his trousers. "What is it you want to tell us?"

Before speaking Mycroft took the seat nearest to Sherlock, crossed his legs and straightened his jacket. "I have something of importance to tell you." He looked at John and frowned at him. "Perhaps it would be best if we were alone."

John was about to stand but Sherlock stopped him. "Whatever you have to say you might as well say it with John present. I'm assuming it's about a case."

"Yes, amongst other things." When it became clear that John wasn't going to leave he continued. "There's been a murder at a local university. A young man, twenty years old." He reached into his pocket and took out several photographs before handing them to Sherlock. "These symbols were found written on the wall next to the body."

Sherlock studied the photos in his hand. "I'm guessing you already know what they mean."

"Of course."

He handed the photos over to John. The first few pictures showed a bloodied corpse on a floor. It was obvious, even to John, that the death had been due to a sharp object being plunged repeatedly into him. There was also an awful lot of blood. The last picture however was different. It showed a white wall, empty apart from several symbols painted in what seemed to be blood. "What do they mean?" he asked.

"It's Greek. The rough translation is avarice." At John's blank look he continued. "It means greed." He turned back to Mycroft. "What else? Their must be more to it then a murder and some Greek symbols."

Suddenly Mycroft seemed uncomfortable. "When the police arrived at the crime scene there was already a young woman lying unconscious near the body. She was holding the knife that was used to kill him." Reaching once again into his pocket he took out another photograph. "The police think she did it but I have my doubts."

Sherlock took the picture and John watched as the blood drained from his face. His eyes flicked back and forth between his brother and the photo. "Is this some kind of joke?" he snapped.

"I'm afraid not."

John was once again confused. "What is it?"

Sherlock stood up, shoving the photo into John's hands. He studied it carefully, quickly realising that it must have been a photo of the girl Mycroft had been talking about. The girl in question had black, curly hair that reached her shoulders. Her complexion was pale and her cheekbones were high. In fact, she reminded him of…

Mycroft interrupted before he could complete the thought. "It's true, Sherlock, you have a younger sister."

John's mouth opened in surprise at Mycroft's words. He looked at the faces of both brothers, expecting one of them to start laughing. However, Sherlock was running his hands angrily through his hair whilst pacing irritably and Mycroft was staring at him with an emotion that John had never seen on his face before. It took him a moment to place it. Mycroft was feeling guilty.

Sherlock spoke suddenly. "Why was I not told about this?"

"It didn't seem important." Sherlock scoffed but let Mycroft continue. "It was an unexpected pregnancy. Mother knew that you wouldn't react well to the news. Of course, she was going to tell you after Anna was born but after your little 'problem' she felt as if it was best you didn't know. Once Anna had moved out it simply didn't seem important."

Sherlock sat down abruptly and pressed his fingers to his mouth, deep in thought. It was several minutes before he spoke again. "I need to see the crime scene."

Even Mycroft seemed surprised at the sudden change in conversation. "The crime scene?"

"Yes, the crime scene. That _is_ what you wanted me to do? Solve the murder."

"Of course." He stood suddenly. "There's a car already waiting outside for you." He made to move towards the door but turned back to look at Sherlock, almost as if he was going to say something. However he changed his mind at the last moment, pausing to pick up his umbrella before leaving.

The silence that followed was uncomfortable and would have stretched on for a long time if John hadn't spoken first. "What the hell just happened?"

Sherlock looked at him as if he'd lost his mind. "Really, John. Is it becoming that hard for you to keep up? I never thought you to be a genius but I thought you could at least keep track of a simple conversation."

"I'd hardly call that a simple conversation. You just found out you've got a sister."

He shrugged offhandedly. "It's irrelevant." Grabbing his coat he slipped it on before winding his scarf around his neck. "We have a murder to solve. Now are you coming or not?"

Sherlock walked out of the room, not bothering to turn around to see if John was following. Of course he knew John was coming, curiosity always got the better of him.

* * *

><p><strong>This is my first Sherlock fanfiction so I'm unsure of how it turned out. I'm open to suggestions and constructive criticism, and of course reviews are always welcome.<strong>

**In case anyone cares, here are the Greek symbols - Φιλαργυρία.**


	2. Chapter 2

**Sinner**

**Chapter 2**

They arrived at the crime scene within fifteen minutes, mainly due to Sherlock's expert knowledge of London's streets. John was glad that he didn't have to sit in the taxi with Sherlock anymore as the silence had been long and awkward, with Sherlock deep in his thoughts for the whole ride.

When they arrived Sherlock stepped out of the taxi and blanked Lestrade before walking into the University, meaning that John was left to apologise to Lestrade before running after him.

The scene that lay before them as they stepped into the University corridor where the body lay was surprisingly gruesome, despite the fact that there was only one body. There was a large amount of blood covering the floor where the body lay. It was the body itself however that made John want to look away, despite having been used to death on a regular basis. When the knife had plunged repeatedly into the body, it seemed to have been stopped by several major organs. The killer hadn't seemed to care. The stomach and spleen were currently hanging out of the body.

Sherlock didn't seem to have the same qualms as John did, as he stepped up to the body and stared peering intently at it. Before Sherlock could touch the body Lestrade appeared at his side with a pair of gloves.

Sherlock snapped them on impatiently before looking back at the body and deducing out loud. "His name was Robert. Twenty three years old. The burn on his left hand and the grease on shirt indicate that he worked at a fast food restaurant. Must've been part time if he was at the University. The shirt he's wearing is reasonably smart meaning he was about to go out. However the shirt he's wearing isn't smart enough for a formal occasion, so a date."

"Sherlock."

He ignored Lestrade. "He's obviously not gay so he was on a date with a girl. She must have been at the University; otherwise he wouldn't have been killed in the corridor. He must have been on the way to meet her." He stood and span around several times before pointing back the way they'd just come. "He must have come from this direction judging by the way he landed."

"Sherlock."

"The only things that we passed on the way here were several lecture halls, a coffee shop and a pub. He doesn't seem like the type that drank coffee so they were going to the pub. "

"Sherlock!"

"What?" he barked back.

"He was going on a date with Anna Wilson. She confirmed it."

He blinked several times before nodding. "Of course." He looked back to the body, a slight frown on his face. John could tell that he was annoyed about Lestrade interrupting him.

"He put up a fight." Sherlock continued, turning over the dead mans arm. "It's strange though. The bruises on his arm indicate that he was held back by someone before he was killed. A woman wouldn't have been able to hold back a man like this."

"So you're saying she didn't do it?"

"No. She could have easily received help from someone. Another boyfriend of hers perhaps. Either way there were two people involved." His eyes roamed across the man's chest. "He died quickly. The first knife wound was to the heart, meaning he was probably dead before he even knew what was happening. When was he found?"

"At around five this evening. One of the lecturers found him."

"That would explain why the murder was so quick. The lecture hall closest to here was where Psychology was being taught and they finished at quarter past five."

"How did you work out that?"

"The design of this building is different from the others around campus. Psychology would have been one of the last subjects added to this University. Therefore it would have been taught in the newest buildings. That and the fact that I looked in one of the classes as we walked past. They were obviously Psychology students. The sign outside the door told me when they finished."

"That's fantastic," John exclaimed.

Sherlock shrugged nonchalantly but smirked.

Lestrade interrupted, wanting to get the conversation back onto the murder. "Do you think she did it then?"

"I'd have to speak to her to find out anything else."

He stood up and turned away from the body, indicating he was done.

"What about the symbols on the wall?" John asked.

Sherlock sighed, not even bothering to turn around as he deduced. "It was written by a man, probably no taller than me judging from where it is on the wall. It wasn't written in a rush, meaning that the message was important. It's most probably relating to the fact that he was cheating on her. Rather boring to be honest."

"He was cheating on her?"

"Yes. Come on John, keep up."

"Hang on, why Greek?" John interrupted, confused once again.

Sherlock's narrowed gaze turned to John. "What?"

"Why was the message written in Greek symbols?"

It took Sherlock a while to reply as he thought about it. "He studied history so perhaps he was interested in Greek mythology. Maybe the killer thought it would be some kind of joke. It's hardly important."

"But you said the message was written carefully as if the message was-"

"Don't twist my words, John," he interrupted.

"I'm not," he argued.

He was ignored as Sherlock pressed his hands together, deep in thought.

John gave him a moment before talking. "Thought of something?"

Sherlock shook his head and turned to Lestrade. "When can we talk to Anna?"

Lestrade frowned slightly but replied. "Now, I guess."

"Well, let's be off then. We have a murder to solve."

* * *

><p>Somehow they'd managed to beat Lestrade to the police station, meaning they were forced to wait outside for him. Sherlock had tried and failed to get into the interview room, having been stopped by several police officers after trying to use Lestrade's ID.<p>

When Lestrade finally arrived he led them through to a small interview room, with Sherlock complaining constantly about how he had better things to do then waiting around.

As they stepped outside the room, John looked through the small hole in the window to see the young woman sitting inside. She looked almost exactly the same as in her photo apart from the dark bags under her eyes.

"What has she told you so far?" Sherlock asked, peering into the room along with John. John could tell that he was already deducing everything he could about her and knowing Sherlock he probably already knew her whole life story.

"She says that she was on her way to meet him when she blacked out. The next thing she says she remembers is waking up next to the body with knife in her hands."

"Right," and with that Sherlock opened the door and walked into the room, John following behind him.

The girl looked up as they entered, her eyes narrowed in confusion. She obviously hadn't been expecting what she saw as she took in John and his jumper, and Sherlock in his long coat.

"Did you kill him?" Sherlock asked bluntly as he towered in front of Anna.

"No," she answered assuredly, folding her arms across her chest and leaning back in her chair.

"Are you sure? You were covered in blood and the knife was in _your_ hands."

"I didn't kill him. Why would I? He was my boyfriend."

"Good question. Did you find out he was cheating on you?"

Her eyes widened in shock. "He was cheating on me?" she exclaimed. "

"Ah, you didn't know."

"I knew it! That bastard."

"That's a dead man you're talking about. I wouldn't be talking negatively about him. I might get suspicious."

It was only then Anna seemed to really look at them and her eyes narrowed once again, this time in suspicion. "You're not police officers are you." There was no hint of a question in her voice.

"Of course not," Sherlock muttered distractedly, waving the comment off. "But did you kill him?"

"No!" she shouted suddenly. "How many times do I have to say it?"

Sherlock stared at her for a moment, with her staring defiantly back, before he let out a long sigh. "She didn't do it."

Both John and Anna were shocked at the sudden change.

"How can you tell?" John asked, not doubtful of Sherlock's statement but curious.

"Her eyes," he answered, as if it was obvious. To Sherlock it obviously was.

Before John could question him further Lestrade burst into the room. "There's been another murder."

Sherlock looked at John, his lips curling up into a small smile. "Looks like we have a serial killer on our hands. Oh, I love a good serial killer."

John glared him, fully intending to tell him off, but suddenly found himself smiling as well. "Ah, yes. It has been a while." And suddenly they were both laughing, with Anna and Lestrade looking at them as if they were crazy.

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><p><strong>AN: Not too sure about this chapter, especially the ending. If you find any mistakes please let me now or have any feedback, then it would be greatly appreciated. Thank you for the story alerts!**

**Next chapter will be centred around Anna and her P.O.V.**


End file.
